Ipswich and Leeds were left vying for the final spot with Leicester already confirmed as league winners.
Kieran McKenna's side needed just a point in their last game, or for Leeds to drop points in their fixture against Southampton - with that game ultimately finishing 2-1 to the Saints.
Goals from Wes Burns and Omari Hutchinson secured the victory for Ipswich in front of a raucous Portman Road crowd.
"It means a lot, mostly seeing how much it means to everyone, the players, the supporters," McKenna told Sky Sports after the result.
"To be one of the leaders of that is absolutely massive. It's a wonderful day, I'm very, very proud of everyone involved.
"We've delivered a really good performance, it's what we've done all year - it's served us well.
"It's an incredible amount of effort. I'm sure it'll sink in in a couple of days.
Ipswich's most famous fan Ed Sheeran, who sponsors the club's shirts, was not in attendance for wild scenes of celebration at Portman Road as fans poured on to the pitch and lit blue flares at full-time.
The Suffolk club, which was sold to American investors for just £40 million, will now pocket at least £200 million in television revenue in the coming years.
Huddersfield had already been realistically relegated prior to Saturday due to their vastly inferior goal difference compared to their rivals at the bottom.
Burns settled any nerves among the home support when he fired low into the bottom corner on 27 minutes.
On-loan Chelsea winger Hutchinson has been one of the stars of Ipswich's season and made sure Kieran McKenna's men could relax by smashing home a second just three minutes into the second half.
Ipswich could face a fight just to hold on to the highly-rated McKenna, a former first-team coach at Manchester United.
The 37-year-old Northern Irishman has been linked with a move to Brighton should Roberto De Zerbi leave the Seagulls.
The results mean Leeds are forced to settle for the play-offs alongside Southampton, West Brom and Norwich.
It will mark their first time back in England's top flight since the 2001/02 season, with the club at one point dropping to the third tier of the football pyramid amid threats of administration and financial turmoil.
The Tractor Boys become the first team to earn back-to-back promotions from League One to the Premier League since Southampton achieved the feat in 2012.
The win for Ipswich also condemned Huddersfield to relegation to League One, where they will be joined by Birmingham and already-relegated Rotherham.
